Java 使用选项卡式活动中的bundle将值从活动传递到片段
我是一名java文盲,仍在努力开发一款适合我个人使用的应用程序。 我从android studio的“选项卡式活动”开始,除了MainActivity中的一个片段和一个捆绑包外,其他大部分都没有改变 这是我的密码: main活动Java 使用选项卡式活动中的bundle将值从活动传递到片段,java,android,bundle,Java,Android,Bundle,我是一名java文盲,仍在努力开发一款适合我个人使用的应用程序。 我从android studio的“选项卡式活动”开始,除了MainActivity中的一个片段和一个捆绑包外,其他大部分都没有改变 这是我的密码: main活动 public class MainActivity extends AppCompatActivity { private static final int REQUEST_PERMISSIONS_REQUEST_CODE = 34; private
public class MainActivity extends AppCompatActivity {
private static final int REQUEST_PERMISSIONS_REQUEST_CODE = 34;
private static final String TAG = MainActivity.class.getSimpleName();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//FloatingActionButton fab = findViewById(R.id.fab);
Bundle bundle = new Bundle();
bundle.putDouble("loclat", 25.4358);
bundle.putDouble("loclang",81.8463);
Fragment SunFragment = new SunFragment();
SunFragment.setArguments(bundle);
setContentView(R.layout.activity_main);
SectionsPagerAdapter sectionsPagerAdapter = new SectionsPagerAdapter(this, getSupportFragmentManager());
ViewPager viewPager = findViewById(R.id.view_pager);
viewPager.setAdapter(sectionsPagerAdapter);
TabLayout tabs = findViewById(R.id.tabs);
tabs.setupWithViewPager(viewPager);
}
}
SectionsPagerAdapter
public class SectionsPagerAdapter extends FragmentPagerAdapter {
@StringRes
private static final int[] TAB_TITLES = new int[]{R.string.tab_text_1, R.string.tab_text_2, R.string.tab_text_3};
private final Context mContext;
public SectionsPagerAdapter(Context context, FragmentManager fm) {
super(fm);
mContext = context;
}
@Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a PlaceholderFragment (defined as a static inner class below).
//return PlaceholderFragment.newInstance(position + 1);
switch (position) {
case 0:
return new SunFragment();
//return PlaceholderFragment.newInstance(pos + 5);
case 1:
return PlaceholderFragment.newInstance(1);
//return SecondFragment.newInstance();
//return PlaceholderFragment.newInstance(pos + 1);
default:
return PlaceholderFragment.newInstance(2);
}
}
@Nullable
@Override
public CharSequence getPageTitle(int position) {
return mContext.getResources().getString(TAB_TITLES[position]);
}
@Override
public int getCount() {
// Show 2 total pages.
return 3;
}
}
最后是SunFragment,我希望从MainActivity获得捆绑数据:
public class SunFragment extends Fragment {
List<SunSession> sunsList;
Typeface sunfont;
Double Dlat;
Double Dlang;
//to be called by the MainActivity
public SunFragment() {
// Required empty public constructor
}
private static final String KEY_LOCATION_NAME = "location_name";
public String TAG ="SunFragment";
public String location;//="No location name found";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Retrieve location and camera position from saved instance state.
if (savedInstanceState != null) {
location = savedInstanceState.getCharSequence(KEY_LOCATION_NAME).toString();
System.out.println("OnCreate location "+location);
// Dlat = getArguments().getDouble("loclat");
//Dlang = getArguments().getDouble("loclang");
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View rootView = inflater.inflate(R.layout.fragment_sun, container, false);
//onSaveInstanceState(new Bundle());
if (getArguments() != null) {
Dlat = getArguments().getDouble("loclat");
Dlang = getArguments().getDouble("loclang");
} else {
Dlat=23.1;
Dlang=79.9864;
}
Log.e("Lat", Double.toString(Dlat));
公共类SunFragment扩展片段{
列表列表;
字体;
双Dlat;
双德朗;
//由主活动调用
公共部门{
//必需的空公共构造函数
}
私有静态最终字符串KEY\u LOCATION\u NAME=“LOCATION\u NAME”;
公共字符串TAG=“SunFragment”;
公共字符串位置;//=“未找到位置名称”;
@凌驾
创建时的公共void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
//从保存的实例状态检索位置和相机位置。
如果(savedInstanceState!=null){
location=savedInstanceState.getCharSequence(KEY_location_NAME).toString();
System.out.println(“OnCreate位置”+位置);
//Dlat=getArguments().getDouble(“loclat”);
//Dlang=getArguments().getDouble(“loclang”);
}
}
@凌驾
创建视图上的公共视图(布局、充气机、视图组容器、,
Bundle savedInstanceState){
//为该碎片膨胀布局
视图根视图=充气机。充气(R.layout.fragment\u sun,容器,false);
//onSaveInstanceState(新Bundle());
如果(getArguments()!=null){
Dlat=getArguments().getDouble(“loclat”);
Dlang=getArguments().getDouble(“loclang”);
}否则{
Dlat=23.1;
Dlang=79.9864;
}
Log.e(“Lat”,Double.toString(Dlat));
我一直在关注博客,但没有传递任何价值。请帮忙
注意:这是一个更详细的问题,据我所知,需要显示更多代码。在您的
main活动中,您的sunFragment
未使用。请删除此部分:
/*Bundle bundle = new Bundle();
bundle.putDouble("loclat", 25.4358);
bundle.putDouble("loclang",81.8463);
Fragment SunFragment = new SunFragment();
SunFragment.setArguments(bundle);*/
您必须在SectionsPagerAdapter
内将bundle
设置为fragment
case 0:
Bundle bundle = new Bundle();
bundle.putDouble("loclat", 25.4358);
bundle.putDouble("loclang",81.8463);
Fragment sunFragment = new SunFragment();
sunFragment.setArguments(bundle);
return sunFragment;
但是如果需要将bundle
从MainActivity
设置为fragment
。然后使用回调
。这样可以将数据从MainActivity传递到fragment
MainActivity onCreate方法
adapter = new Adapter(getChildFragmentManager());
SquadsTeamListFragment teamA =
SquadsTeamListFragment.newInstance(teamAData,teamBData
adapter.addFragment(teamA, teamAName);
viewPager.setAdapter(adapter);
tabLayout.setupWithViewPager(viewPager);
在主要活动中使用此适配器
static class Adapter extends FragmentStatePagerAdapter {
private final List<Fragment> mFragmentList = new ArrayList<>();
private final List<String> mFragmentTitleList = new ArrayList<>();
Adapter(FragmentManager manager) {
super(manager);
}
@Override
public Fragment getItem(int position) {
return mFragmentList.get(position);
}
@Override
public int getCount() {
return mFragmentList.size();
}
void addFragment(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
@Override
public CharSequence getPageTitle(int position){
return mFragmentTitleList.get(position);
}
}
正如您在上一个问题中所写的,您是否仍然收到错误?Fragment-SunFragment=new-SunFragment();
以及您将此片段实例传递到SectionsPagerAdapter
的位置?当getArguments()失败时,错误不在那里,因为我在片段本身中传递了一个值Dlat和Dlang。问题是getArguments()总是null@grabarz121:我没有理解你。我应该如何传递实例?我链接的源代码没有显示任何内容。请解释它为空,因为SunFragment
内部SectionsPagerAdapter
的实例与你在MainActivity
中创建的实例不同。谢谢。这正在工作。只有一个问题:这是std是这样做的还是只是一种变通方法?实际上这取决于您的需求。在您当前的需求中,这是可以的。但在某些情况下,需要以不同的方式进行设置。
public static SquadsTeamListFragment newInstance(String playerList, String
oppPlayerList) {
SquadsTeamListFragment fragment = new SquadsTeamListFragment();
Bundle args = new Bundle();
args.putString(ARG_TEAM_DATA, playerList);
args.putString(ARG_OPP_TEAM_DATA, oppPlayerList);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
playerList = getArguments().getString(ARG_TEAM_DATA);
oppPlayerList = getArguments().getString(ARG_OPP_TEAM_DATA);
}
}